1. Field of the Invention
This invention relates to a method and apparatus for performing a recording/reproduction of an information on/from an optical recording medium having recording tracks each defined by wobbled grooves.
2. Description of the Related Art
Generally, in a recordable or rewritable optical recording medium, a rotation control information and/or an address information are recorded by means of the wobbled grooves in advance. In other words, a rotation and/or address information are preformatted on the wobbled grooves. An example of the optical recording medium having the wobbled grooves as mentioned above includes a DVD-RAM(digital versatile disc-random access memory) as shown in FIG. 1.
In the DVD-RAM of FIG. 1, there are formed wobbled grooves 10 and lands 12 wobbled alternately with the wobbled grooves 10. The grooves and lands 10 and 12 are used as recording regions. A certain period of wobbling signals are included in a wobbled portion 14 of each groove and land 10 and 12, hereinafter referred to as "wobbled part", that is, in each side of the land and groove 10 and 12. A recording/reproducing apparatus for an optical recording medium generates a rotation control information about the DVD-RAM and a recording clock by means of the wobbling signals. Also, each of the land and groove 10 and 12 is alternated with a identification(ID) region consisting of a pre-pit train 16. The pre-pit train 16 includes an address information for indicating the physical position of the groove and land 10 and 12. The physical positions of all the grooves and lands 10 and 12 are indicated by means of such ID regions, thereby recording an information on all the grooves and lands 10 and 12.
In order to detect the wobbling signal from the optical recording medium having such wobbled lands and grooves 10 and 12, the optical recording/reproducing apparatus makes use of a band pass filter(BPF) having a filtering characteristic corresponding to a frequency band of the wobbling signal. In an optical recording/reproducing apparatus employing such a BPF, the wobbling signals are not detected when a rotation speed of the optical recording medium is different from a reference speed. Also, an optical recording/reproducing apparatus including a BPF having a filtering characteristic corresponding to an optical recording medium in a specified rotation speed mode fails to detect the wobbling signal from the optical recording when it drives an optical recording medium in a different rotation speed mode. In other words, an optical recording/reproducing apparatus can not be used changeably for all optical recording media in various rotation speed modes. Moreover, the optical recording/reproducing apparatus including a BPF having a specified filtering characteristic fails to drive an optical recording medium at a certain of multiple speed because it can not detect the wobbling signal from the optical recording medium when the optical recording medium is driven at a speed different from the reference speed.